The invention relates generally to a heating unit. More particularly, the invention relates to a heater with modules that may be selectively energized for heating zones or portions of zones.
Various types of heating units have been developed for rapidly radiantly heating objects to a high temperature such as around 1500xc2x0 F. One such radiant heater is described in U.S. Pat. No. 3,525,850, which discloses a foil ribbon adapted to be heated by electricity to a temperature in the range of about 1200xc2x0 F. to 1800xc2x0 F. U.S. Pat. No. 3,956,612 describes an electrical heater with modular units that may be assembled as an array to accommodate various lengths and widths of objects to be heat processed.
At least one disadvantage found in the prior art is that a radiant heater or a modular array of radiant heaters must be energized in its entirety. If a manufacturer needs only a xe2x80x9climited runxe2x80x9d to produce a small quantity or partial order of goods, use of the older heaters can result in wasted electricity and increased manufacturing costs. With older heaters, the manufacturer may have to choose to: delay smaller orders until additional small or partial orders are received to maximize an entire radiant heater array; decline to accept smaller orders; or incur higher energy costs.
Another potential disadvantage in the prior art is associated with heater maintenance. When an older heater""s heating element fails, for instance, or requires maintenance, the entire heater may be unusable until the heating element is repaired or replaced. This is especially so where the heater elements are interconnected in electrical series. Maintenance xe2x80x9cdown timexe2x80x9d thus can lead to higher costs due to loss of manufacturing productivity.
According to an aspect of the invention, a heating unit is disclosed which has a housing and heating modules that may be joined contiguously in the housing. Each of the heating modules may have an electrical connection attached and each may have a heating element such as a foil that can be heated to a high temperature by passage of electricity through the foil. Preferably, an electrical power control apparatus is provided to selectively energize each electrical connection, which in turn selectively energizes the heating module to heat its foil element.
In another aspect of the invention, the heating unit preferably has connection elements for releasably connecting heating modules to each other. In this manner, the heating unit may be more easily maintained by removing and repairing or replacing heating modules without affecting the operability of other heating modules.
According to another aspect of the invention, a heating unit is provided which is capable of selectively heating multiple zones. As in the previously described embodiment, the heating unit has a housing and a plurality of heating modules and radiant heating elements adapted to be electrically heated to a high temperature. In this embodiment, the heating modules may be arranged in any relative geometry. For instance, the heating modules may be disposed laterally to one another, or both laterally and longitudinally, as required, to provide a variable arrangement for radiant heat. Variably arrayed geometries are possible since each heating module can be selectively and individually energized.
To selectively and individually energize each heating module, the heating unit has means for selectively energizing the modules. Preferably, the energizing means includes an electricity source wire that can be energized to supply electricity to the radiant heating element or connected to neutral so that the radiant heating element is not energized. The energizing means may also include means for selecting any number of electricity source wires. The selecting means may be a controller device, or group of devices, that serves to govern electrical power to be delivered to the wires.
According to another aspect of the invention, a method is disclosed for rapid heat processing. The method includes the steps of arranging radiant heating modules in spaced relationship to each other; selectively energizing any of the radiant heating modules using an electrical control apparatus; and providing the radiant heat at a predetermined temperature for a predetermined time.
The disclosed method may include the substeps of energizing at least two of the radiant heating modules and adjusting current between them such that a temperature differential exists across the radiant heating modules.
Additional substeps may include selecting phase, for example, on line one (L1) to supply electricity to one of the heating modules and selecting neutral on line two (L2) for another heating module.
Another aspect of the disclosed method may include removing and repairing or replacing a heating module while other heating modules remain operable to reduce production down time.
Other aspects and advantages of the invention will be apparent from the following description and the attached drawings, or can be learned through practice of the invention.